1. FET Amplifier Circuits Analysis
FET amplifier parameter gm
CS amplifiers
CS with RS amplifiers
SF amplifiers
Bootstrap amplifier
CG amplifiers 1

2. Types of FET amplifiers (MOSFET)
(a) Common Source (CS)
High AV and high Ri
Voltage amplifications
(b) Common Source (CS) with RS
Low AV and high Ri
Stability applications
(c) Source Follower (SF)
Very low Ro and high Ri
Buffer applications
(d) Common Gate (CG)
Very low Ri and high AV
High Frequency applications 2

3. FET amplifier parameter gm
MOSFET-self-bias amplifier 3

4. FET amplifier parameter gm
MOSFET-voltage divider-bias amplifier 4

5. Example: Find gm of the given FET amplifier5

6. Example: Find gm of the given FET amplifier6

7. CS amplifier analysis Rin = RG Ro = RD MOSFET-self-bias CS amplifier
MOSFET-voltage divider-bias CS amplifier
Rin = RG
Ro = RD 7

8. CS with RS amplifier analysis
JFET-self-bias CSwithRS amplifier
MOSFET-voltage divider-bias CS withRS amplifier
approximate
Rin = RG
Ro = RD 8

9. SF amplifier analysis Rin = RG Ro = RS//1/gm
JFET-self-bias SF amplifier
MOSFET-v.divider-bias SF amplifier
Rin = RG
Ro = RS//1/gm 9

10. Example: 10

11. Bootstrap Amplifier analysis
Miller’s Theorem
Rin 11

12. Miller’s Theorem applied to Bootstrap amplifier
Rin
Miller’s resistor RG is connected between Vin and Vo2 12

13. Example: Find Rin of the following Bootstrap CS amplifier
1. Find gm
2. Find Vo1/Vin=AV1
3. Find Rin = RM1 13

14. CG Amplifier MOSFET-self-bias CG amplifier
MOSFET-voltage divider-bias CG amplifier 14

15. CG amplifier analysis 15